Hand-piece for injection device with a retractable and rotating needle

ABSTRACT

An injection device is arranged and constructed to simultaneously rotate a needle during its forward translation as a therapeutic agent such as a liquid is ejected therefrom. In one embodiment the injection device is an automatic device including a pump forcing the liquid through a tube to a hand-piece. The needle has a first position in which it is disposed within a housing of the hand-piece, and a second position in which the needle extends outwardly of the hand-piece so that it can be used to eject the liquid, with the needle being automatically uni- or bi-directionally rotated as it is advanced between the first and second positions. In an alternate positions a syringe is provided with a barrel, a plunger extending into the barrel to eject the liquid through the needle, and a plunger which is pushed into the barrel by the operator.

RELATED APPLICATIONS

This application claims priority to provisional applications Ser. No.60/133,397 filed May 10, 1999 and Ser. No. 60/173,374 filed Dec. 28,1999.

This application is a divisional of application Ser. No. 09/506,484filed Feb. 17, 2000, now U.S. Pat. No. 6,428,517, incorporated herein byreference.

BACKGROUND OF THE INVENTION

I. Field of the Invention

This invention pertains to a hand-piece for an injection device orsimilar apparatus used to inject a therapeutic fluid into human oranimal tissues, and more particularly to a hand-piece which includes aneedle movable along a longitudinal axis, which needle is optionallyrotating about said axis as well.

II. Description of the Prior Art

It is well documented in both dental and medical literature that pain,tissue damage and post-op complications have long been tolerated asnegative side effects from the use of existing hypodermic drug deliveryinjection systems. The pain and tissue damage are as a direct result ofuncontrolled flow rate in conjunction with excessive pressures createdduring the administration of drug solutions within the tissues.Subjective pain response of a patient has been demonstrated to beminimized at specific flow rates during the administration of a drug.Also, it has been scientifically demonstrated that particular pressures(excessive without occlusion, per se) for a specific tissue type willcause damage. It is therefore critical that a specific flow rate inconjunction with a specified pressure range be maintained during thedelivery of fluids (drugs) when a subcutaneous injection is givenpreventing subjective pain response as well as tissue damage. It is alsonecessary that this system have the capability to aspirate undercontrolled conditions of rate and pressure to avoid the same negativeside effects during fluid movement. U.S. Pat. No. 5,180,371 to Spinello,incorporated herein by reference, presented an invention which allowed arate to be set for the drug via a hypodermic needle disposed in ahand-piece.

One of the goals of dentistry and medicine should be to administer careto patients in the most humane and painless manner. The sine qua non ofany treatment is to produce a desired result without causing damage orpain to the individual. Therefore there is an important need in allfields of surgery for an injection system which can be used toadminister a fluid while causing substantially no pain or tissue damageto the patient.

Another goal of dentistry and medicine in general is to insure thatduring any procedure involving interaction between a dentist or othercare giver and a patient, utmost care is taken to protect the care giverfrom injury and/or infection with diseases.

The use of hollow-core needles is the standard in drug delivery inmedicine and dentistry. The use of the hollow-core needle dates backover 150 years when Charles Pravaz, a French general surgeon, patentedsuch a device. It has been recognized that the use of hypodermicneedles, which activity is endemic in the field, is one particularlyhazardous activity which could cause injury. More particularly, the useof a hypodermic needle in dentistry and other medical fields has beenshown to put the operator at risk to inadvertent needle stickspresenting a potential high risk to infection disease transmission forhealth care workers.

Currently, there are several auto-retraction type syringes are knownthat provide increased safety by allowing the protruding needle to beretracted into a protective sheath after use. However, current syringesrequire the use of a palm-thumb grasp during their use. This type ofhand dexterity presents a potential risk of inadvertent needle stickduring entry and withdrawal from the patient tissues. Other syringes areprovided with removable caps. However, this configuration does not solvethe problem in a satisfactory manner.

All of these prior art references have either one or more of thefollowing deficiencies.

-   -   1) The use of a hollow needle that is rigidly affixed to the end        of a syringe-, tubing or hand-piece. The protruding needle        presents a risk of inadvertent needle stick to the operator.    -   2) Existing auto-retracting syringes and the like require the        operator to use a palm-thumb grasp to operate. This structure        creates an increased risk of inadvertent needle stick to the        operator.    -   3) Existing auto-retracting syringes and the like require the        operator to make use of the hand to physically retract the        needle, thereby, making it difficult and cumbersome to perform.

Some prior art syringes and needles with sheaths or caps are disclosedin the following U.S. Pat. Nos.: 5,120,310; 5,188,613; 5,267,961;5,389,076; 5,423,758; 5,578,011; 5,632,733; 5,637,092; 5,810,775;5,030,209; 4,911,693; 4,900,310; 4,813,426; 4,795,432; 4,664,654;4,695,274; 4,966,592; 4,747,831; 4,900,311; 5,411,487; 5,106,379;5,713,873.

With the rise of infectious diseases, i.e., hepatitis and AIDS,protection of the health care workers has become a needed prioritybecause, as indicated in the medical/dental literature, inadvertentneedle sticks represent a significant risk to our health care providers.In the past 15 years regulatory agencies such as OSHA have attempted toimprove the use and safety of needles in the health care industryfurther accentuating the need for an effective means of preventingneedle sticks.

In addition, various medical organizations have suggested and severalstates have instituted rules for the protection of care givers whileproviding injections to patients. More specifically, rules have beenpromulgated requiring that injection needles on syringes be providedwhich can be easily removed prior to an injection and re-installedimmediately after an injection.

The proposed invention has been designed to eliminate the potential ofinadvertent needle sticks during and after use.

Another related problem addressed by the present invention pertains tothe deflection or bending of needles as they are inserted into thetissues of a patient. This deflection occurs because the needle isusually flexible because of its relatively small cross-sectional areaand cannot resist effectively the axial and radial forces present duringthe insertion. The deflection is undesirable because it providesadditional resistance during the insertion, to the movement of theneedle and makes it difficult to guide the needle to a particular site.Moreover, if a needle is deflected, bent or otherwise deformed duringinsertion, it may cause more pain to the patient, trauma to the localtissues and other undesirable effect. It has been discovered (asdisclosed in co-pending provisional application serial No. 60/173,374filed Dec. 28, 1999), incorporated herein by reference, that thesedisadvantages are eliminated or at least alleviated if the needle isrotated about its longitudinal axis as it is advanced along the axisinto the patient tissues. While rotating devices are known which rotateabout their longitudinal axes to allow drilling through bony tissues,these devices do not allow high level tactile control during use. Othersyringes do not allow the use of a bi-directional rotational insertiontechnique to be used during a power assisted injection process.

OBJECTIVES AND SUMMARY OF THE INVENTION

In view of the above-mentioned disadvantages of the prior art, anobjective of the, present invention is to provide an injection devicehaving a needle which can be selectively advanced from a retractedposition in which the needle is hidden, toward an open position in whicha therapeutic agent can be administered effectively, and can beretracted back to the retracted position before disposal.

A further objective is an injection device adapted to provide injectionto a selected site and/or tissue by using a selective bi-directionalrotational movement of the needle to prevent deflection of the needle.

Yet another objective is to provide an injection device which allows anoperator to advance a needle at a manually controlled rate and with ahand-piece which is held steadily in a relatively stationary positionwith respect to the patient.

A further objective is to provide an injection device which can be usedrepeatedly to advance and retract a needle in a linear, rotational orbi-directional rotational motion.

Other objectives and advantages of the invention shall become apparentfrom the following description.

Briefly, an automatic injection device constructed in accordance withthis invention includes a source of fluid to be injected, a needle,handle with a housing and a coupling used to selectively advance theneedle out of the hand-piece, preferably under the control of theoperator, and once an injection is complete, to retract it back into thehand-piece. Advantageously, the needle may be protracted and retractedseveral times during multiple uses on the same patient. The device maybe a drug delivery device which serves to inject medicament from a tankor reservoir. This includes but should not be limited to infusion typepumps, syringe pumps, such as the Wand® made by Miiestone Scientific ofOrange, N.J.

In one embodiment, of the invention, a spring is provided in the housingwhich is arranged to bias the needle. Preferably the needle is biasedtoward its retracted position so that if the needle is advanced toextend outwardly of the housing and then released, it automaticallyreturns to the retrieved position within the housing thereby reducingthe likelihood that the needle pricks or otherwise injures an operator,the patient, or anyone else. Locking members are also provided which areused to secure the needle in the first—that is— the retrieved position,or the second position. The coupling may be arranged and constructed tocooperate with the housing so that as the needle is advanced out of thehousing, it is automatically and simultaneously rotated about itslongitudinal axis. Typically, the needle may be rotated by about45–270°. Preferably the needle is rotated by about 180°. This may beaccomplished, for instance, by providing a helical groove on an innersurface of the housing and a boss on the coupling. As the coupling movesthrough the housing, its boss rides through the groove and this camingaction causes the coupling, and the needle to rotate. If the groove isoriented in the same direction, the rotational motion isuni-directional. The groove can also be made to change direction one ormore times along its length, in which case the needle undergoes a bi- ormulti-directional motion. The term uni-directional is used to describemotion in the same sense, e.g., clockwise or counterclockwise. The termbi-directional is used to describe a motion that changes sense, e.g.,initially clockwise, then counterclockwise.

Rotation may also be imparted to a needle affixed to a standard syringe.In this case, the needle is mounted to one wall of the barrel using aball-bearing mounted, or other frictionless surface. A plunger iscoupled to the other side of the barrel in a manner which forces theplunger to rotate as it is inserted into the barrel to force liquid fromthe barrel to be ejected through the needle. The plunger and the needleare coupled so that the rotation of the plunger is transmitted to theneedle.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a somewhat schematic diagram of an automatic injectiondevice constructed in accordance with this invention;

FIG. 2 shows a sectional somewhat diagrammatic view of the hand-piecefor the device of FIG. 1 with the needle in an extended position;

FIG. 3 shows a sectional view similar to FIG. 2 with the needle in theretracted position;

FIG. 4 shows a sectional view of the needle and a spring used to biasthe needle toward the retracted position;

FIG. 5 shows a sectional view of the needle and the spring in theextended position;

FIG. 6 shows an embodiment of the invention which allows the needle torotate about its axis, the needle being in a retracted position;

FIG. 7 shows a view similar to FIG. 6 with the needle being in theextended position;

FIG. 8 shows an enlarged view of the needle coupling and its engagementwith a spiral groove;

FIG. 9 shows an enlarged side view of the coupling;

FIG. 10 shows a side view of a hand-piece according to an alternateembodiment of the invention wherein the helical groove has been omitted;

FIG. 11 shows a top view of a hand-piece according to an alternateembodiment wherein the slot holding the button or tab has side wing orwings; and

FIG. 12 shows a sectional view of a hand-piece according to an alternateembodiment of the invention

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In order to better understand the purpose of this invention, a somewhatgeneric automatic injection device is first described. In thisapplication the term automatic injection device, as illustrated in FIG.1 refers to a device 10 in which a fluid ejection means such as a pump12 is used to force a fluid from a tank 14 under the control means suchas a switch 16 into a flexible tubing 18. The tank may be a vial, acarpule or other known vessels that could be used to store a therapeuticliquid. The tubing 18 terminates in hand-piece 20 with a needle 22. Thevarious elements described so far cooperate to allow a nurse, physician,dentist and other health care professional operator to injectselectively the liquid from tank 14 into the tissues of a patient (notshown) by activating the switch 16.

Importantly, according to this invention, the needle 22 is movable intoand out of the hand-piece 20. In a preferred embodiment, the needle 22is normally disposed inside the hand-piece 20 and is extended by theoperator prior to or simultaneously with the injection. After theinjection is complete, the needle 22 is preferably retracted into thehand-piece 20. In this manner, the needle 22 is exposed only the shortperiods of time that the injection actually occurs, thereby preventinginjury and infection to the operator of the device 10 or other people.Studies have shown that a person handling a device associated with aneedle is injured during this period.

Advantageously, the hand-piece 20, needle 22 and the tubing 18 aregenerally disposable. Moreover, the cap normally provided to cover theneedle is eliminated, so it is no longer required.

Details of the hand-piece 20 and needle 22 are now discussed inconjunction with FIGS. 2–9. The hand-piece 20 includes in accordancewith this invention a cylindrical housing 24 with an internal wall 26,an external wall 28, and two ends 30, 32. Hand-piece 20 further includesan elongated hollow stem 34 provided to protect the tubing 18. Thetubing 18 which extends through the stem 34 into the housing 24 and iscoupled directly or indirectly to the needle 20 as discussed more fullybelow. Stem 34 may be glued to the housing 24, or may be sized andshaped to form an interference fit therewith, whereby it can be insertedinto the housing 24 or removed at will.

Mounted on housing 24 there is a control member such as a button 36slidable in a longitudinal slot 38 extending through the housing.Housing 24 is provided with a stop 40 at the forward end of slot 38. Therear end 42 of the housing 24 serves as a rear stop for button 36.Alternatively, a stop similar to stop 40 may be provided on the externalwall 28 of housing 24. Button 36 includes two spring arms 44, 46. Thesearms extend in the longitudinal axis of the housing 24 and are turnedupward, or away from surface 28 at their tips. These arms 44, 46 aresomewhat flexible and cooperate with the stop 40 and end wall 42 tolimit the movement of button 36 in slot 38. More particularly, as button36 is reciprocated by an operator in slot 38, when the button reachesits forward position, the arm 44 rides over the stop 40 and then snapsradially inward to form an interference fit with the stop 40. Thisposition (shown in FIG. 2) corresponds to the extended position of theneedle 20, with the button 36 being locked. The button 36 can bereleased by pressing it downward toward the housing 24, thereby causingarms 44, 46 to flex upward. The button 36 can then move backward, awayfrom the front opening 30 because the arm 44 clears the stop 40. Whenthe button 36 is moved backwards toward stem 34, when its rear arm 46engages the rear wall 42, the button 36 is locked into the rearposition, and the needle 22 is in its fully retracted position, asindicated in FIG. 3.

Button 36 further includes a pin 48 extending downwardly or radiallythrough slot 28 to engage needle 20. Button 38 can be made of a highimpact plastic material. Its wings 44, 46 can be made integral with thebutton 38, or can be made of steel.

Referring now to FIGS. 4 and 5 (in which the stem 34 has been omittedfor the sake of clarity) the needle 20 is attached to a coupling 50.This coupling includes a central hollow shaft 52 sized and shaped toconnect to an end of tubing 18. Preferably the tubing 18 is glued orotherwise secured to the shaft 52 so that it is permanently mountedthereto.

The coupling also has a circular disc 54 mounted coaxially on the shaft52. Spaced axially away from disc 54 there is cup-shaped adapter 56.Adapter 56 has an outer surface 58 with a plurality of axially shapedcircumferential ribs 60. The disc 54 and adapter 56 are separated by anannular space 62 having an axial length which is equal to, or slightlygreater than the cross-sectional dimension of pin 48. The button 36 ispositioned on the housing 12 so that this pin 48 extends into the space62 as shown. Therefore the coupling 50 and the button 36 are effectivelyinterlocked so that the coupling 50 can be moved in either directionalong the length of the housing 24 and the button 36 will move with it(within the length of the slot 38) and vice versa. However, becausespace 56 is annular, the coupling 50 may also rotate around thelongitudinal axis of housing 24 without interference from button 36.

Typically, needle 22 includes a narrow, thin-walled hollow shaft 64 anda base 66. In one embodiment of the invention the needle 22 isconfigured with the base 66 being mounted on shaft 52 so that it abutsthe adapter 50. Base 66 is preferably bonded or otherwise secured to theshaft 52 and/or the adapter 56. The base 66 is hollow and incommunication with the opening in the hollow shaft 64. Therefore, oncethe base 66 is mounted and secured to the adapter 56, the interior oftube 18 is in communication with the interior of the shaft 64 throughthe shaft 52.

Preferably, the end 30 is partially closed with a disc-shaped end wall68. This end wall 68 has an opening (not shown) sufficiently large toallow the needle 22 and its base 66 to extend at least partially fromhousing 24, as seen in FIG. 5.

In one embodiment of the invention, as mentioned above, the base 66 isbonded to adapter 54. In another embodiment of the invention, theadapter 54 is a female Luer connector and the base 66 is a male Luerconnector, the two connectors cooperating to mount the needle 22 on thecoupling 50 so that the needle 22 can be attached and removed at will.This feature may be advantageous during a long procedure the tip of theneedle 22 may become dull and may have to be changed before theprocedure is complete.

In another embodiment of the invention, an optional compression spring70 is provided between the end wall 68 and the coupling 50 in such amanner that normally the spring 70 pushes the coupling 50, and theneedle 22 attached thereto, away from wall 68. In other words, in thisembodiment, the spring 70 urges the needle 22 toward its retractedposition.

Yet in a further embodiment of the invention, shown in FIGS. 6, 7 and 8,the coupling 50 is provided with a boss 72 extending radially, and theinner surface 26 is provided with a helical groove 74, with the boss 72being seated with the groove 74 as shown. In this embodiment, coupling50 and the needle 22 attached thereto are rotatable about thelongitudinal axis of housing 24. Coupling 50 with its boss 72, andgroove 74 define a rotating member that cooperate with the button 36 sothat the translational movement of button 36 along the housing 24 inslot 38 causes a simultaneous translation and rotation of the needle 22as the needle moves between its retracted and protracted positions.

The operation of device 10 is now described in conjunction with thedrawings. Initially, it is assumed that device 10 has a hand-piece whichhas been provided with a spring 70 and groove 74. Prior to an injectionthe needle 22 is disposed in the hand-piece 20 in its retracted positionand is maintained in this configuration by the spring 70. In fact thetubing 18, hand-piece 20 and needle 22 may come in a kit, several kitsbeing made available for the operator, each with a needle having a shaft64 of different nominal lengths (i.e. 20 mm, 25 mm, 30 mm . . . ) In onemode of operation, the operator initializes the pump 12, positions thehand-piece 20 so that the hand-piece points to the site or tissue ofinterest, activates the switch 16 to start the delivery of thetherapeutic agent, and starts advancing the needle 20 to cause theneedle to slowly extend outwardly of the hand-piece and coaxially withthe longitudinal axis of the hand-piece 20. Preferably, the hand-pieceis sized and shaped so that it can be held by the operator in the mannerof a pencil with his forefinger being free to rest on and push thereciprocate button 36. However, before the needle can be pushed forward,it must be unlatched because it is locked in the retracted position bythe cooperation between arm 46 and rear wall 32. Therefore the operatormust release the needle 22. This can be accomplished by pushing down orradially inwardly on the button 36. This action causes the button 36 tobend arms 44, 46 upward thereby releasing arm 46 from rear wall 32. Theneedle 22 is now free to move forward.

As the needle 22 is advancing with respect to the hand-piece 20, theboss 72 rides in a caming action against the helical groove 74 andcauses the coupling 50 and the needle 22 to rotate. This combinedadvancement or translation of the needle and its simultaneous rotationis continued until the button 36 reaches the forward stop 40. At thispoint the forward arm 44 goes over the stop 40 and then forms aninterference fit with it causing the button 36 and the needle 22 to lockin the extended position. This action is felt by the operator as a clickand therefore the operator does not have to keep his eye on thehand-piece. Since the needle 22 has now been locked in the extendedposition, the operator can release button 36 and continue the injectionwithout moving the needle. The therapeutic liquid from tank 14 isinjected into the patient during or after the needle has been advancedout of the housing 24 and into the patient's tissues.

In some situations, an operator may prefer to advance the needle 22 outof housing 24 before inserting the needle into the tissues. In this casehe just moves the button 36 forward while he keeps the hand-piece 20away from the patient until the needle 22 reaches its extended positionand is locked into this position. The operator can proceed to insert theneedle 22 into the patient tissues in a normal manner.

Once, the injection is completed, the needle 22 can be retrieved backinto housing 24. This retrieval may be accomplished either while theneedle is imbedded into the patient's tissues, or after it has beenwithdrawn therefrom. In either case, the needle 22 can be retrieved bypushing the button 36 inwardly or radially causing the arm 44 to riseand disengage from the forward stop 40. Once the arm 44 is disengaged,the operator can release button 36. Since spring 70 is in a compressedstate, as shown in FIG. 5, releasing the button 36 causes the spring 70to extend axially through the housing 24 forcing the coupling 50 to moverapidly backward toward stem 34. Retraction occurs by rotation about thelong axis. Rotation minimizes drug resistance and makes the retractionmore efficient. In this manner, the needle 22 which is attached to thecoupling also moves rapidly backwards and snaps back into the housing tothe retracted position. This operation takes places very fast therebyavoiding any chance that the operator will get pricked or otherwiseinjured by the sharp tip of needle 22. Since the end of tubing 18 isalso attached to the coupling, the tubing 18 slides through the stem 34and in and out of the housing 24 as required.

If the spring 70 is omitted, the needle 22 must be retrieved into thehousing 24 manually using button 36 causing the needle to rotate uponremoval.

As illustrated in FIG. 4, the coupling 50 is provided with ribs 68 anddisc 54 which arranged and constructed to slidably engage the inner wall28 of housing 24. Therefore, as the coupling 24 reciprocates within thehousing in a smooth controlled movement without any radial jitter,thereby giving the operator a solid feel and ease of operation.

Preferably, the tubing 18, hand-piece 20 and needle 22 are alldisposable. Health regulation frequently require that disposable itemswith sharp tips or edges which may puncture an attendant must bedisposed separately. As indicated in FIG. 9, preferably the portion ofthe shaft 52 extending between disk 54 and adapter 56 is provided with aradial groove 76 which may be about 0.015″ deep. At the end of theinjection procedure, the stem 34 may be removed from the housing 24, andthe housing 24 may be bent manually to cause the coupling 50 to snapalong groove 76. The disc 54 can now be removed from the housing 24while the adapter 56 and the needle 24 are retained in the housing 24 bythe pin 48. The housing 24 with the needle 22 can now be disposed as asharp object while the remaining portions including tubing 18, stem 34can be disposed as standard (i.e., non-sharp) objects.

In the Figures, the groove 70 is shown as being uni-directional so thatas the needle is advanced, it is rotated by the groove always in thesame direction, e.g, clockwise. In an alternate embodiment, the groovecan be made into axially spaced segments with adjacent segments beingoriented in different senses. For this arrangement, as the needle istranslated along its axis, it is simultaneously rotated first in onedirection, then in the opposite direction by the respective groovesegments. This the needle can have a uni-directional, bi-directional ormulti-directional rotation.

As discussed above, the helical groove 74 is optional. If it is omitted,then the coupling 50 can have a much simpler shape, or can be eliminatedaltogether. For example, FIG. 10 shows an embodiment wherein the tubing18 abuts the base 66 of needle 22. The button 36 or in this case, asimple tab 38A extends through slot 38 and is engaged to the tubing 18.Instead of an end wall 68, or in addition thereto, an annular springstop 68A is provided on the inner wall 28 of housing 24. Spring 70 is incompression between this stop 68A and the base 66 of needle 22. If thehousing 24 is made without the groove 74, as shown in FIG. 10 then theneedle 22 can be advanced and retrieved linearly, i.e., withoutimparting to it any substantial rotary motion about its longitudinalaxis.

In the embodiments of FIGS. 1–9, the button 36 is limited to alongitudinal motion by the shape of slot 38. FIG. 10 shows an alternateembodiment of the invention. In this embodiment, the button 36 or a tabis disposed in a longitudinal slot 36A having a lateral extension 38B.In this embodiment, after the needle 22 reaches its extended position,the operator shifts the button 36 into lateral extension 38B. The forceof spring 70 applied to the base 66, and hence to tubing 18, forces theneedle to be locked in this position until it is released. If desired, asecond lateral extension 68C may also be added to park the needle in theretreated position so that it does not move.

In the embodiments of FIGS. 1–11 a liquid injecting device 10 isdescribed wherein liquid from a separate tank is pumped through aflexible tubing 18 and hand-piece 20 to needle 22. In an alternateembodiment of the invention, some of the novel features of device areincorporated into a standard syringe-type liquid delivery system. Inthis embodiment, a syringe 100 is provided having a barrel 102 having afirst end wall 104 with finger tabs 106. A hole 108 is made in the wallwith two opposed radial arms 110. Extending through hole 108 there isprovided a plunger 112 formed of a rod 114. At one end, rod 114 isformed with a head 116 and a thumb ring 118. Inside head 116 there is astationary disc 120 and bearings 122 attached to rod 114. Rod 114 isformed with one or more helical grooves 124.

At the opposite end, rod 114 is formed with a harpoon 126. Next to theharpoon, there is a piston 130 with an O-ring 132 and being attached torod 114.

At the other end of barrel 102, there is provided an end wall 126 withan opening 128. A sleeve 130 passes through the opening 128 and isprovided with two disc-shaped walls 132, 134. Ball bearings or otherfrictionless couplings support the sleeve 130 and walls 132, 134 on endwall 126 in a rotatable manner. A connector 136 is mounted on wall 134to receive needle 22. When the needle 22 is mounted on connector 136 byits base 66, a portion 22A of the needle extends into the barrel 102.

The syringe 100 is used to eject a liquid such as an anesthetic disposedin a cartridge 140. This cartridge 140 includes a glass cylindricalhousing 142, with a membrane 144 at one end and a rubber stopper 146 atthe other end.

The end wall 104 on syringe 100 is removable to allow the cartridge 140to be inserted into the barrel 100 with the membrane 144 disposed nearend wall 126 and being engaged by wall 132. Once the cartridge 140 isinside the barrel and an operator is ready for the injection, theoperator mounts the needle 22 on connector 136, its portion 22A entersinto the barrel 102 and penetrates the membrane 144. Next, the end wall104 is replaced on the barrel so that the harpoon 126 penetrates andengages the stopper 146. The operator then starts the injection bypushing the needle 22 forward to penetrate the subject tissues. Duringthe forward movement of the needle, the operator holds the syringe withtwo fingers on the tabs 106 and the thumb engaging ring 118 and pushingthe rod forward. During this motion, the rod is slowly advanced into thebarrel 102, forcing the piston into the housing 142. The piston and thestopper both move forward expressing liquid from the cartridge 140through the needle 22. Importantly, the positioning of the groove(s) 124and tabs 110 in opening 108, the caming action of tabs 110 on groove(s)124 causes the rod 114 to rotate around its longitudinal axis, whichalso coincides with the longitudinal axis of the barrel 102. Therotation of the rod 114 is transmitted by the harpoon 126, piston 128and O-ring 130 to the cartridge 140 and then through the end wall 132 toneedle 22. Thus the needle 22 rotates essentially in the same manner asthe rod 114.

The rotation imparted to the needle 22 attached to either hand-piece 20or syringe 100 is dictated by the pitch and length of the grooves 74 and124 respectively. It has been found that preferably, the needle throughits travel should rotate by about 45–270°. More particularly, it hasbeen found that the rotational movement is most effective when it coversabout 180°.

An important advantage of the present invention, is that it allows aclinician to hold the hand-piece within a grasp similar to one used forholding a pen or pencils, i.e., between the thumb, the forefinger andthe middle finger. Traditional grasps for injection devices, such asstandard syringes, involve the use of the fore- and middle fingerholding the barrel and the opposed thumb moving toward the fingers andapplying pressure on the piston. This grasp is not very efficientbecause it is difficult for a clinician to hold a syringe steady or toadvance it at a slow, controlled rate while the fingers are movingtoward each other. Moreover, it is believed using this processrepeatedly over several hours a day may cause carpal syndrome. On theother hand, in the present invention, the hand-piece is held between thethumb and the middle finger. The forefinger is used to steady thehand-piece, to direct it more precisely toward the desired tissues andto move the needle. Thus, the present invention provides a much moreergonomic device.

The subject invention discloses of a novel approach for injectionsystems in which a needle can be presented to the patient in a retractedstate, thereby protecting the operator prior to the entry of the needleinto patient tissues. Once the injection procedure has been concludedthe needle can be withdrawn automatically back into the protectivehousing prior to having the hand-piece being moved away from patient'stissues, thereby eliminating the exposure of the operator to theunprotected needle at all times.

The novel design allows the reuse of a needle on a particular patient,i.e., subsequent dental injections during the same appointment can begiven for a patient using the same device.

The subject invention provides the following advantages over the priorart:

A. Allows the needle to automatically retract into the protectivehousing.

B. Allows the operator to advance the needle out of the housing sheathvia manual operator control.

C. Allows the operator to use a pen-like grasp which has been shown tohave superior tactile control and more ergonomic then existingconfigurations.

D. Does not require extensive hand manipulation or the use of the secondhand to automatically retract the needle.

E. Allows for reuse of the needle on the same patient during a givenprocedure, but eliminates the risk associated with the re-use of aneedle.

F. Depending on the structure of the hand-piece, the needle can besubjected to a translational motion or a simultaneous translational androtational motion.

G. Depending on the structure of the hand-piece, the needle can besubjected to uni-directional, bi-directional or even multi-directionalmotion.

H. The injection process described can be repeated several times ofnecessary with ease, with the same or a different needle.

This invention represents a major advancement in the safety and use ofhollow-core needles. It discloses a device that is easy and predictablein operation. The device minimizes or eliminates the risk potential ofinadvertent needle sticks to health care workers.

While several embodiments have been described it should be understoodthat other modifications can be made to the invention without departingfrom its scope as defined in the appended claims.

1. An injection system for injecting a liquid such as a therapeuticagent into a patient, said system comprising: a source of liquid; ahand-piece remote from said source and adapted to be held by theoperator during an injection procedure; a coupling having a first, asecond end, and a grove disposed therebetween: a tubing connected tosaid second end; said hand-piece including a hollow housing and a needlesupported by said housing and having a first position wherein saidneedle is disposed in said housing and a second position in which saidneedle is disposed at least partially outside said housing to providethe injection, said needle being coupled to said first end of saidcoupling; and a control member disposed on said hand-piece and coupledto said coupling; wherein said needle is selectively movable betweensaid first and second positions by said control member; and wherein saidhandpiece and said coupling cooperate to cause said needle to translateand rotate simultaneously as said needle is moved along at least asubstantial portion of the path between said first and second positionsto prevent said needle from bending; and wherein said coupling isbreakable along said groove to allow said tubing to be removed from saidhand piece and leaving said needle trapped within said hand-piece. 2.The system of claim 1 further comprising a first stop cooperating withsaid handle to secure said needle in said first position.
 3. The systemof claim 2 further comprising a second stop cooperating with said handleto secure said needle in said second position.
 4. The system of claim 1further comprising a spring biasing said needle toward one of said firstand second positions.
 5. The system of claim 4 wherein said spring biassaid needle toward said first position, whereby when said needle isreleased from said second position it automatically returns to saidfirst position.
 6. The injection device of claim 1 wherein said housingincludes a longitudinal slot and a button sliding in said slot, saidbutton being coupled to said needle to move said needle between saidfirst and said positions.
 7. The injection device of claim 6 furthercomprising a first locking element that cooperates with said housing tolock said needle in said first position.
 8. The injection device ofclaim 7 further comprising a second locking element cooperating withsaid housing to lock said needle in said second position.
 9. Theinjection device of claim 8 wherein said button cooperates with one ofsaid first and second locking elements to release said needle from saidfirst and second positions, respectively.
 10. The injection device ofclaim 6 further comprising a spring disposed in said housing, saidspring being arranged to bias said needle toward one of said first andsecond position.
 11. The injection device of claim 10 wherein saidspring is arranged to bias said needle toward said first positionwhereby said needle automatically returns to said first position whenreleased from any position external of said housing.